Different cardiac and renal inhibitory and excitatory areas in rabbit hypothalamus

The hypothalamic area was stimulated in anesthetized rabbits at a large number of selected points, and the effects on the simultaneously recorded right cardiac sympathetic nerve activity (CSNA) and renal nerve activity (RNA) were analyzed quantitatively. Four characteristic patterns of CSNA and RNA responses could be observed. The most striking finding was the presence of opposite responses of CSNA and RNA at many hypothalamic stimulus points, in addition to the conventionally observed CSNA and RNA responses in the same direction. By a new method, we drew hypothalamic maps for CSNA and RNA response magnitudes. These maps show that the excitatory areas of CSNA and RNA are surrounded by respective inhibitory areas. Although the excitatory areas of CSNA and RNA correspond with each other on the right side, they are not identical on the left side. These data suggest that the heart and kidney are controlled by sympathetic nerve activities originating from different hypothalamic neural groups in the rabbit.